Mounting arbor for saw cutting blades

ABSTRACT

A mounting for use in mounting rotating cutting blades to the drive shaft of saws is provided. The mounting is an arbor or arbor sleeve having a non-symmetrical outer mounting surface onto which is mounted a cutting blade which contains a similarly configured mounting hole. The arbor or arbor sleeve is designed for use with a cutting blade having a mounting hole which, when viewed from one side of the blade is the same as the outer surface mounting surface, and which viewed from the other side of the blade is not the same. The use of the arbor or arbor sleeve of the present invention with a cutting blade having these characteristics results in the blade being mounted on the saw in only one orientation.

This application is a continuation of U.S. patent application Ser. No.08/340,614, filed Nov. 16, 1994, which was a division of U.S. patentapplication Ser. No. 08/186,030, filed Jan. 25, 1994, now U.S. Pat. No.5,373,834 which was a continuation of U.S. patent application Ser. No.07/863,708, filed Apr. 3, 1992 and issued as U.S. Pat. No. 5,303,688 onApr. 19, 1994.

FIELD OF THE INVENTION

The present invention relates to a mounting device for rotating sawcutting blades. More specifically, the invention relates to a speciallyconfigured arbor and correspondingly configured aperture in a circularconcrete saw blade to prevent the cutting blade from being mismounted onthe saw.

BACKGROUND OF THE INVENTION

Circular saw blades are normally driven by rotating shafts connected tomotors. In many applications, the rotating cutting blades have circularholes through the center for acceptance of a circular drive shaft. Theshafts often have a smaller diameter mounting portion which extends froma larger primary portion of the drive shaft to form a shoulder. Theblades are typically pressed over the smaller diameter mounting portionuntil they are stopped against the shoulder formed by the main driveportion of the shaft. The blade is then locked onto the shaft byclamping it between the shoulder on the main portion of the drive shaftand either a threaded locking nut which is threaded onto the end of thesmall diameter mounting portion or a bolt threaded into a threaded holein the end of the shaft. The friction from the clamping force preventsthe blade from rotating with the shaft.

Often times, material is allowed to enter the hole in which the clampingbolt is threaded. This prevents the bolt from being tightenedsufficiently into the threaded hole in the shaft. When this occurs,there is an insufficient clamping force to hold the rotating cuttingblade against the shoulder, and because the mounting is circular, theblade may slip. When the blade slips with respect to the shaft, theblade speed often decreases rapidly, causing spalling or chipping of theconcrete surface adjacent groove being cut.

In order to remedy this problem, non-circular arbor sleeves, or cuttingblade mounting members, can be attached to the drive shafts. The arborsleeves are normally securely mounted to the drive shaft, so they do notrotate. For example they can be clamped, welded, pinned to the shaft,keyed, or held by set screws. A surface of the arbor sleeve is used asthe surface upon which the rotating cutting blade is then mounted. Thecutting blade is configured to have a mounting hole of the same size andshape of the arbor to allow it to be positioned over the arbor to bedriven by the motor drive shaft.

Arbor sleeves are normally square or a circular shaft with symmetricflutes,-although they may have other symmetric configurations. The shapeof the arbor sleeve is symmetrical on its outer surface, in order thatthe cutting blade may be easily mounted on it without much alignmenteffort. When a non-circular arbor sleeve is employed, the cutting blademay not slip, as the hole of the blade and the outside of the arborsleeve have sides which contact one another.

Alternatively, the drive shaft can be configured to have a symmetricnon-circular end, and the cutting blade configured to have acorrespondingly shaped hole through which the arbor can be inserted.While it is possible to have the blade mounting area of the drive shaft,or arbor, itself be machined into the desired shape, sleeves are moreeasily machined at lower cost.

Because-the arbors or arbor sleeves are symmetrical in shape, thecutting blade may be mounted so that either side of the cutting bladefaces the saw. Normally, the person installing the saw will orientatethe cutting blade so the teeth on the blade are in the correctorientation relative to the direction the saw is to travel duringcutting. For wood cutting saw, the saw teeth orientation is apparent,and the blade can be easily orientated to rotate in the correctdirection relative to the direction that the saw will travel duringcutting.

With concrete cutting saws, however, the teeth do not have a readilyapparent directional orientation. Concrete cutting saw blades are madewith diamond impregnated cutting segments that are symmetrically shaped.When used to cut hardened concrete and when water lubricated, the bladescan be used in either orientation, or with either side of the bladetoward the saw when the saw is traveling in the same direction. Thus theorientation of the water lubricated blade on the saw does not matter forcured, hardened concrete.

When the same blade is used to cut wet or very green concrete withoutwater lubrication, however, the blade orientation is important. Thecutting segments are formed by having harder cutting media, such asdiamond chips or tungsten carbide particles, being placed in a softersupport or binding matrix, such as bronze or other softer metals. Thecutting segments are either formed on the metal support disk, or formedseparately and then bonded to the support disk. After the cuttingsegments are on the disk, the cutting segments are dressed by slightlyabrading the cutting segments to remove enough of the binding matrix toexpose the cutting particles. This dressing typically leaves one side ofthe cutting particles exposed while the opposite side has a trail of thesofter binding matrix extending from the cutting particle (FIG. 10). Ifthe cutting blade is rotated so that the exposed side of the particlesface the direction of the blade rotation, the blade cuts well. If,however, the blade is orientated the other way so that the exposedportion of the cutting particles face away from the direction of theblade rotation, then the cutting blade will not cut well because onlythe binding material and not the clotting particles contact theconcrete. This will also occur if the blade is not dressed sufficientlyand the cutting particles are not exposed adequately before cutting.When the blade is mismounted or is insufficiently dressed, chattering ofthe blade and spalling and/or chipping of the concrete occurs when theblade is used to cut the concrete. Further, because the blade is notwater lubricated when cutting wet or very green concrete, the frictioncreated between the concrete and the binding material causes extremeheat build-up, causing the blade to warp, which in turn damages thesurface of the concrete surrounding the cutting blade. In some cases,the heat build-up combined with the chattering of the warped blade willcause the cutting segments to detach from the blade. This situation isdangerous, as the cutting segments may be propelled into the user andcause injury, or be propelled into and damage the saw.

Previously, cutting blades used to cut wet concrete were labeled withnotices such as "this side out," to insure correct orientation of theblade on the saw. That labeling, however, is not always effective. Thereis thus needed a way to insure correct orientation of a circularconcrete cutting saw blade on the saw, and a way to guard againstrotation of the saw blade relative to the drive shaft.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided a specially shaped mounting for use with rotating cuttingblades and cutting saws having drive shafts, which is especiallysuitable for concrete cutting saws and blades. The mounting ispreferably on located an arbor sleeve, although it may be located on anarbor itself. The sleeve is configured so that its shape cooperates witha hole in the cutting blade to allow the blade to be mounted on thesleeve in only one orientation. The arbor sleeve of the presentinvention is located on a drive shaft of a saw and used to rotated thecutting blade. The drive shaft of the saw has a shoulder, and a threadedportion, all along a longitudinal axis.

The arbor sleeve has a proximal and distal end, the 0proximal end beinglocated nearer the saw. The arbor sleeve has a shaft mounting memberwith a longitudinal hole therein sized to accommodate the insertion ofat least a portion of the drive shaft. A flange extends radially outwardfrom the shaft mounting member. The flange prevents the cutting bladefrom sliding along the shaft.

A blade mounting member or mounting surface is also provided on thearbor sleeve. The blade mounting member is the mounting surface on whichthe cutting blade is mounted. The blade mounting member is locateddistal of the flange on the sleeve. The blade mounting member has aprimarily triangular exterior or outer surface and a circular bore inits middle for acceptance of a motor drive shaft. Two of the triangulars ides of the blade mounting member are substantially straight, thesetwo sides being advantageously connected at their intersection by agenerally rounded or arcuate corner. The third side of the triangularblade mounting member is convex in shape, and connects with the firstand second sides at generally rounded or arcuate corners. The threesides of the triangle are of unequal length.

The blade mounting member thus has a non-symmetrical shape about an axisorthogonal to the longitudinal axis through the center of the hole, andabout which the mounting member rotates during cutting.

The arbor sleeve of the present invention is designed to be used with arotating cutting blade having a plurality of concrete cutting segmentslocated about the periphery of the disc. The blade has a first side anda second side, and a mounting hole therein for mounting the blade to thedrive shaft for rotation of the blade about a longitudinal axis throughthe hole.

The hole in the blade, when viewed from the first side, is the same asthe shape of the blade mounting member. The hole is non-symmetric inshape, however, such that when viewed from one direction along thelongitudinal axis can not be rotated about the longitudinal axis so asto coincide with the shape of the hole when viewed from the otherdirection along the longitudinal axis. Thus, the blade will fit onto thearbor sleeve in only one orientation.

One specific configuration of the blade mounting member has a centerpoint with a horizontal and vertical axis therethrough. For orientationpurposes, it is to be understood that "in front of" the vertical axismeans to the right of the vertical axis or in the positive horizontaldirection, and "behind" the vertical axis means the opposite thereof;"above the horizontal" means on top of the horizontal axis or in thepositive vertical diretion, and "below" the horizontal means theopposite thereof. A first corner of the triangle is located at a radiusR1 which emanates from a point located a distance D1 away from thecenter point in front of the vertical and along the horizontal axis. Asecond corner is located at a radius R2 such that R2 approximatelyequals 1.2 R1, and emanates from a point located behind the verticalaxis a distance D2 away from the center point and at an angle θ of about54 degrees above the horizontal axis. The distance D2 approximatelyequals 0.93 D1. A third corner of the triangle has a radius R3 such thatR3 approximately equals 1.06 R1, and emanates from a point locatedbehind the vertical axis a distance D3 away from the center point and atan angle α of about 66 degrees below the horizontal axis. The distanceD3 approximately equals 0.89 D1. A first side of the triangletangentially connects the outside of the first and second corners, and asecond side tangentially connects the outside of said second and thirdcorners. A third side, having a radius R4 emanating from a pointedlocated in front of the vertical axis a distance D4 away from the centerpoint and at an angle β of about 9 degrees above the horizontal axis. D4approximately equals 1.32 D1, where said third side tangentiallyconnects the outside of said first and third corners.

In accordance with another aspect of the present invention, there isprovided a method of orienting the rotating concrete cutting blade onthe drive shaft in the correct orientation. The method comprisesproviding a blade mounting member which is non-symmetrical when rotated180 degrees about an axis orthogonal to the longitudinal axis of thedrive shaft about which the blade rotates during cutting. A hole isprovided in the blade, where the hole when viewed from the first side ofthe blade is the same as the shape of the blade mounting member, but notwhen viewed from the opposite side of the blade. The blade is thenplaced on the blade mounting member so that the hole in the bladecoincides with and fits over the blade mounting member, and the blade issecured to the shaft. Advantageously, the blade is secured by placing awasher on the shaft distal of the blade, and then placing a nut on thethreaded portion of the shaft whereby the nut provides a clamping forceto clamp the blade between the washer and the flange of the sleeve.

This method and apparatus prevents the user from attaching the rotatingcutting blade to the arbor sleeve in an incorrect orientation. Thus,cutting blades used to cut wet or green concrete may not be mismountedso as to cut in the wrong direction and cause chipping and spalling, andwill not overheat and warp, further causing damage to the concrete. Thearbor sleeve of the present invention will also help prevent the use ofa cutting blade which is not designed for use with a concrete saw whichis fitted with this arbor. In this manner, users will be prevented fromaccidentally using a cutting blade which was not intended for use withthe particular concrete saw.

Further objects, features, and advantages of the present invention willbecome apparent from the detailed description of the drawings whichfollows, when considered with the attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an arbor sleeve, washer, nut, driveshaft and motor, and a cutting blade with a mounting hole therein inaccordance with the present invention.

FIG. 2 is a front view of the arbor sleeve of FIG. 1.

FIG. 3 is a sectional side view of the arbor sleeve of FIG. 1.

FIG. 4 is a front view of the cutting blade of FIG. 1 mounted on thearbor sleeve of FIG. 1.

FIG. 5 is a rear view of the cutting blade of FIG. 1 laid over the arborsleeve of FIG. 1.

FIG. 6 is a sectional view of the shaft, arbor sleeve, washer and nutalong line 6--6 of FIG. 1.

FIG. 7 is a dimensional front view of a blade mounting member.

FIG. 8 is a front view of a blade mounting member having a trapeziumshape.

FIG. 9 is a perspective view of an arbor sleeve, drive shaft, motor,cutting blade, washer, and mounting bolt in accordance with an alternateembodiment of the present invention.

FIG. 10 is a partial perspective view of a cutting blade as known in theprior art.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Referring to FIGS. 1-3 and 6-7, there is shown the mounting of the:present invention in the form of an arbor sleeve 10. The arbor sleeve 10is for use with a saw, such as a concrete saw 12 having a motor 14. Adrive shaft 16 is rotated by the motor 14 about the longitudinal axis ofthe shaft 16. The drive shaft 16 has a free end 18 for acceptance of acutting blade 21. The free end 18 of the drive shaft 16 extends to ashoulder 19 with a smaller threaded shaft 20 extending longitudinallyfrom the shoulder 19 away from the saw 12. In the context of a concretecutting saw, such as that described in U. S. Pat. No. 5,056,499, thedrive shaft 16 is turned such that the blade 21 will cut in an up-cutdirection, as shown relative to the direction of travel 27 of the saw12. In general, the arbor sleeve 10 has a proximal end 23 and a distalend 25 relative to the saw 12, with the proximal end 23 being closer tothe saw 12 and the distal end 25 being further away. The arbor sleeve 10also has a shaft mounting portion 22, a blade mounting member 24, and acentral bore 26 therethrough.

The shaft mounting portion 22 is generally cylindrical in shape, and islocated at the proximal end 23 of the arbor sleeve 10. The shaftmounting portion 22 has an outer diameter of about 0.81 inches (20.6 mm)and a length of about 0.39 inches (9.9 mm). The length is primarily afunction of the desired contact area between the drive shaft 16 and thearbor sleeve 10. The outer diameter is only slightly larger than thediameter of the shaft 16 upon which the arbor sleeve 10 is mounted. Theshaft mounting portion 22 is the part of the arbor sleeve 10 which isused to connect the sleeve to the free end 18 of the drive shaft 16. Theshaft mounting portion 22, as illustrated, is secured to the free end 18of the drive shaft 16. The mounting portion 22 may be welded, orattached by screws, pins, friction or other means known to those skilledin the art so as to prevent rotation of arbor sleeve 10 relative toshaft 16. When the arbor sleeve 10 is mounted onto the drive shaft 16,the shoulder 19 advantageously abuts with the distal end 23 of thesleeve.

A blade support flange 30 extends radially outward from between theshaft mounting member 24 and the blade mounting member 26. The bladesupport flange 30 is also cylindrical in shape, but has a largerdiameter than the mounting portion 22. The flange 30, as illustrated,has an outer diameter of about 1.5 inches (38.1 mm). The flange 30 has athickness of about 0.22 inches (5.6 mm). The flange 30 is sized toprevent the cutting blade 21 from sliding past the blade mounting member24 and along the drive shaft 16. The central bore 26 passes through thecenter of the flange 30 as well.

The blade mounting member 24 contains a specially shaped mountingsurface of the arbor sleeve 10. The blade mounting member 24, asillustrated, is generally triangular in shape, with three sides ofunequally length and rounded corners. Advantageously, two of the sidesare substantially straight while the third side is convex. The blademounting member 24 thus has three sides 34, 36, 38, joined at threecorners 40, 42, 44, and with the central bore 26 running therethrough.The mounting member 24 may be defined from a center point 28 located atthe center of the bore 26 and an arbitrary horizontal axis H andvertical axis V running through this center point. For orientationpurposes, it is to be understood that "in front of" the vertical axis Vmeans to the right of the vertical axis V or in the positive horizontaldirection, and "behind" the vertical axis V means the opposite thereof;"above the horizontal" means on top of the horizontal axis H or in thepositive vertical diretion, and "below" the horizontal axis H means theopposite thereof. The longitudinal axis of rotation passes through thecenter point 28.

Referring to FIG. 7, the first corner 40 is, as illustrated, rounded,having a radius R1 of about 0.135 inches (3.4 mm), the radius extendingfrom a first point 41 located in front of the vertical along thehorizontal axis H (or at an angle of 0 degrees along the horizontal axisH) a distance D1 of about 0.487 inches (12.4 mm) from the center point28. The second corner 42 is also rounded, having a radius R2 of about0.163 inches (4.1 mm). The radius of the second corner 42 extends from asecond point 43 located behind the vertical axis V, being a distance D2of about 0.447 inches (11.4 mm) from the center point 28 and at an angleθ of about 54 degrees above horizontal axis H. The third corner 44 isalso rounded, having a radius R3 of about 0.143 inches (3.6 mm). Theradius of the third corner 44 extends from a third point 45 locatedbehind the vertical axis V, being about 0.432 inches (11.0 mm) from thecenter point 28 and at an angle α of about 66 degrees below thehorizontal axis H.

The first side 34 is substantially straight, and as illustrated,connects the first corner 40 and second corner 42 in a tangent fashion,thus having a length of about 0.830 inches (21.1 mm). The second side 36is also generally straight, connecting the first corner 42 and thirdcorner 44 in a tangential fashion, thus having a length of about 0.771inches (1.96 mm).

The third side 38 is arcuate in shape, having a radius R4 of about 1.095inches (27.8 mm). The radius of the third side 38 extends from a fourthpoint 46 located in front of the vertical axis V, being a distance D4 ofabout 0.644 inches (16.4 mm) from the center point 28 and at an angle βof about 9 degrees above the horizontal axis H. The third side 38intersects the second corner 42 and third corner 44 in a tangentialfashion.

The central bore 26 has a radius of about 0.313 inches (7.9 mm),radiating about the center point 28. The shaft bore 26 may, of course,be a different diameter, depending on the diameter of the drive shaft 16on which it is to be mounted.

As defined from the center point 28 dimensions of the blade mountingmember 24 may be assigned as follows. The first corner 40 radius (R1),second corner 42 radius (R2) and third corner 44 radius (R3) have arelation such that R2 approximately equals 1.2 R1 and R3 approximatelyequals 1.06 R1. The distance from the center point 28 to the first point41 (D1), second point 42 (D2) and third point 43 (D3) is such that D2approximately equals 0.93 D1 and D2 approximately equals 0.89 D1 whenthe lines from the center point 28 to each point 41, 43, 45 are alongabout the same angle as defined above.

The first side 36 and second side 34 are of such a length as tointersect the outside of corners 40, 42, 44 in a tangential fashion. Thethird side 38 is of such a radius as to intersect the outside of thesecond corner 42 and third corner 44 in a tangential fashion, when thefourth point 46 is along the angle defined above and a distance D4 ofabout 1.32 D1. The central bore 26 has a radius RB equal to about 2.32times R1.

While blade mounting member 24 is generally triangular in shape, it isnot symmetric. Scalene triangular shapes, where each side is a differentlength, are believed advantageous.

Referring to FIGS. 1, 4 & 5, the cutting blade 21 has a first distalside 48, second proximal side 50, and a mounting hole 52 therein. Themounting hole 52 is shaped so that when the cutting blade 21 is viewedfrom its distal side 48, the hole 52 has the same shape as the blademounting member 24 and is only larger in size to the extent necessary toallow the blade to be positioned on the mounting member 24. A toleranceof about 0.002 to 0.003 inches (0.05 to 0.08 mm) between the size of thehole 52 and mounting member 24 works well. In this manner, the cuttingblade 21 may be mounted on the blade mounting member 24 of arbor sleeve10 as illustrated in FIG. 4.

Referring to FIGS. 1 and 6, once placed on the arbor sleeve 10, theblade 21 is secured by placing a washer 54 distally of the blade on thethreaded end 20 of the drive shaft 16. The washer 54 is, as illustratedin FIG. 6, a metal disk having a hollow center section which faces theblade and a center hole to allow the passage of the smaller diameterthreaded shaft 20 therethrough. A nut 56 is then positioned on thethreaded smaller shaft 20 of the drive shaft 16 and tightened so as topress the blade 21 between the peripheral portion of washer 54 and theflange 30 of the arbor sleeve 10. As shown in FIG. 6, friction from theclamping force exerted by nut 56 prevents rotation of the sleeve 10 andblade 21. Alternatively, the sleeve 10 can be secured to shaft 16 aspreviously described. For illustration, a set screw 55 is shown inphantom in FIG. 6 being inserted into hole 57 in shaft 16. The nut 56and washer 54 could also be combined into one part rather than twoseparate pieces.

As illustrated in FIG. 9, the blade 21 may alternatively be secured by athreaded bolt 58 engaging a threaded hole 59. In this embodiment, thedrive shaft 16 does not have a threaded portion 20, and instead has thethreaded hole 59 in its end along its longitudinal axis. The blade 21 ispressed between the flange 30 of the sleeve 10 and the washer 54 by thebolt 58 which is tightened into the hole 59 in the shaft 16. Once again,the washer 54 and the bolt 58 could be formed as one piece an operate inthe same manner.

The mounting hole 52, as illustrated, corresponds in shape to the blademounting member 24 and will not be repeated in detail. The hole 52 iscreated by punching from the cutting blade 21 the mounting member 24shape. The hole 52 could also be created by machining. It is to beunderstood that the dimensions detailed above for the sleeve 10 and forthe hole 52 may be varied moderately and still achieve the same shapesand tolerances.

As can be seen in FIGS. 1, 4 & 5, the blade 21 can only be mounted uponthe arbor sleeve 10 in one orientation. As stated previously, thecutting blade 21 is manufactured so that it will only cut properly ifrotating in one specific direction. As illustrated, the cutting blade 21is machined such that when the first side 48 faces away from the saw 12,the blade will cut in the correct up-cut direction. As shown in FIG. 5,if a user attempts to position the cutting blade 21 on the arbor sleeve10 in a position where the second side 50 of the blade faces away fromthe saw 12, the blade 21 will not fit on the mounting member 24. This isbecause when the blade 21 is flipped over, the blade mounting member 24and the hole 52 in the blade 21 have shapes that no longer coincide.This feature is provided by having the blade mounting member 28 of thearbor sleeve 10 and the mounting hole 52 in the cutting blade 21 benon-symmetrical, so that the mirror image of the hole 52 or member 24 isnot the same as the shape of the hole 52 or member 24 viewed directly.

It will now be apparent to one skilled in the art given the abovedisclosure, that in order to accomplish the desired task of preventingthe cutting blade 21 from being mismounted, any number of shapes forblade mounting member 24 are possible. The primary requirement in orderto prevent mismounting is that the blade mounting member 28 andcorresponding mounting hole 52 be of a non-symmetrical shape when viewedfrom opposite sides along the longitudinal axis, as illustrated bycomparing FIGS. 4 & 5 where the blade 21 is rotated 180 degrees aboutvertical axis V (FIG. 7). This can be accomplished by the asymmetrictriangular shape discussed above, but four or more sided figures willalso work. In particular, an arbor or arbor sleeve with blade mountingmember having a trapezium shape could work (FIG. 8 ) . Such shapes alsoneed not necessarily have straight sides, as the mounting above doesnot. A three sided arbor or arbor sleeve 10 is preferred, however,because it reduces machining costs. Further, the fewer number of sidesmakes it easier for the user to mount the blade 21 on the sleeve 10, asthere are fewer blade 21 and sleeve 10 positions which must be eithervisually or manually eliminated in order to find the correct alignment.

As will be apparent to one skilled in the art, the shape of the blademounting member 24 may be machined directly on the end of the driveshaft 16 itself (not shown), instead of being formed on a sleeve 10which is then secured to the shaft 16.

Further, while the mounting has been described here in use with aconcrete cutting saw 12 and corresponding concrete cutting blade 21, itis contemplated that the mounting have uses in conjunction with variousother cutting methods and devices.

There is thus provided a means and method for preventing a cutting bladefrom being mismounted on a saw. There is provided an arbor or arborsleeve 10 on the drive shaft 16 of a saw 12. The blade mounting member24 of the arbor sleeve 10 has a mounting surface 24 shaped so that whenviewed directly and in a mirror, the shapes cannot coincide. Themounting hole 52 in the cutting blade's 21 first side 48 has a shapewhich corresponds to that of the mounting member 24. The cutting blade21 is pressed onto the mounting member 24 of the sleeve 10 with thefirst side 48 facing away from the saw 12, as is the only orientation inwhich the blade 21 will fit onto the sleeve 10. The washer 54 is thenplaced on the shaft 16 against the first side 48 of the blade 21, andthe nut 56 is threaded onto the smaller portion of the shaft 20 tosecure the blade 21 to the sleeve 10 between the washer 54 and theflange 30.

Alternatively, the blade 21 may be secured by inserting the threadedbolt 58 into the hole 59 in the shaft 16 in order to press the blade 21between the washer 54 and the flange 30, as was discussed above.

It will be understood that the above described arrangements of apparatusand the methods therefrom are merely illustrative of applications of theprinciples of this invention and many other embodiments andmodifications may be made without departing from the spirit and scope ofthe invention as defined in the claims.

What is claimed is:
 1. A rotating concrete cutting blade having amounting hole in said blade comprising three sides joined at threecorners, the hole encompassing the rotational axis of the cutting blade,the location of the first corner being defined by a first arc subtendedbetween about 20° and 160° from a point lying on the plane of the bladeabout 12 mm from said axis, said first arc having a radius of about 3 to4 mm, the location of the second corner being defined by a second arcsubtended between about 20° and 160° from a point lying on the plane ofthe blade about 11 mm from said axis and about 126° clockwise from saidfirst point, said second arc having a radius of about 4 mm, the locationof the third corner being defined by a third arc subtended between about20° and 160° from a point lying on the plane of the blade about 11 mmfrom said axis and about 119° clockwise from said second point, saidthird arc having a rad/ius of about 3 to 4 mm.
 2. A rotating concretecutting blade having a centrally located mounting hole that has atriangular shape formed by first, second and third sides, the first andsecond sides of the hole intersecting at an angle of about 56°, thesecond and third sides intersecting at an angle of about 59°, and thethird and first sides intersecting at an angle of about 65°.
 3. Aconcrete saw with a rotating arbor comprising:an exterior, rotatingmounting surface connected to the arbor, the surface comprising agenerally triangular shape with three sides of unequal length comprisingtwo substantially straight sides and one convex side; and a concretecutting blade connected to the generally triangular shaped surface torotate with the arbor.
 4. A concrete saw with a rotating arborcomprising:an exterior, rotating mounting surface connected to thearbor, the surface comprising a generally triangular shape with threesides of unequal length, the generally triangular shape comprising across-sectional shape which, when viewed along a rotational axis aboutwhich the generally triangular surface rotates, has a rotational axiswith a horizontal axis and vertical axis therethrough, a first cornerhaving a radius R1 which emanates from a point located a distance D1away from the rotational axis in front of the vertical axis and alongthe horizontal axis, a second corner having a radius R2 such that R2approximately equals 1.2R1 which emanates from a point located behindthe vertical axis a distance D2 away from the rotational axis and at anangle of about 54 degrees above the horizontal axis, where D2approximately equals 0.9 D1, a third corner having a radius R3 such thatR3 approximately equals 1.1 R1 which emanates from a point locatedbehind the vertical axis a distance D3 away from the rotational axis andat an angle of about 66 degrees below the horizontal axis, where D3approximately equals 0.9 D1, a first side which tangentially connectsthe outside of said first and second comers; a second side whichtangentially connects the outside of said second and third corners, anda third side having a radius R4 emanating from a point located in frontof the vertical axis a distance D4 away from the rotational axis and atan angle of about 9 degrees above the horizontal axis, such that D4approximately equals 1.3 D1 and said third side tangentially connectsthe outside of said first and third comers; and a concrete cutting bladeconnected to the generally triangular shaped surface to rotate with thearbor.
 5. A concrete saw comprising:a rotating arbor having an exteriormounting surface connected to it so as to rotate with the arbor, theexterior surface having a generally triangular shape with three sides ofunequal length comprising two substantially straight sides and oneconvex side; and a rotating concrete cutting blade having an apertureconfigured to fit on the generally triangular shaped surface so that itis rotated by the arbor.
 6. A concrete saw comprising:a rotating arborhaving an exterior mounting surface connected to it so as to rotate withthe arbor, the exterior surface having a generally triangular shape withthree sides of unequal length, wherein the generally triangular shapecomprises a cross-sectional shape which, when viewed along a rotationalaxis about which the arbor rotates, has a rotational axis with ahorizontal axis and vertical axis therethrough, a first corner having aradius R1 which emanates from a point located a distance D1 away fromthe rotational axis in front of the vertical axis and along thehorizontal axis, a second corner having a radius R2 such that R2approximately equals 1.2R1 which emanates from a point located behindthe vertical axis a distance D2 away from the rotational axis and at anangle of about 54 degrees above the horizontal axis, where D2approximately equals 0.9 D1, a third corner having a radius R3 such thatR3 approximately equals 1.1 R1 which emanates from a point locatedbehind the vertical axis a distance D3 away from the rotational axis andat an angle of about 66 degrees below the horizontal axis, where D3approximately equals 0.9 D1, a first side which tangentially connectsthe outside of said first and second corners; a second side whichtangentially connects the outside of said second and third comers, and athird side having a radius R4 emanating from a point located in front ofthe vertical axis a distance D4 away from the rotational axis and at anangle of about 9 degrees above the horizontal axis, such that D4approximately equals 1.3 D1 and said third side tangentially connectsthe outside of said first and third corners; and a rotating concretecutting blade having an aperture configured to fit on the generallytriangular shaped surface so that it is rotated by the arbor.
 7. Arotating concrete cutting blade having an aperture on the rotationalaxis of the cutting blade so the blade can mount on an arbor, theaperture having a generally triangular shape with three sides of unequallength, wherein the three sides comprise two substantially straightsides and one convex side.
 8. A rotating concrete cutting blade having arotational axis and an aperture on the rotational axis of the cuttingblade so the blade can mount on an arbor, the aperture having agenerally triangular shape with three sides of unequal length, whereinat least one of the sides is substantially straight, and wherein none ofthe side comprise a plurality of lines joined at an angle.
 9. A rotatingconcrete cutting blade having a centrally located mounting hole that hasa generally triangular shape formed by first, second and third sides,the first and second sides of the hole intersecting at an angle of about56°, the second and third sides intersecting at an angle of about 59°,and the third and first sides intersecting at an angle of about 65°, andwherein one of the sides is arcuate.